Intraframekoding

Intraframekoding, often referred to as intra-frame compression, is a video compression technique that exploits spatial redundancy within a single video frame. Unlike inter-frame compression, which also looks at differences between consecutive frames, intra-frame coding processes each frame independently. The primary goal is to reduce the amount of data required to represent a single frame by identifying and eliminating this spatial redundancy.

This is typically achieved through a combination of techniques. Transforms, such as the Discrete Cosine Transform (DCT), are commonly used to convert spatial pixel data into a frequency domain representation. In this domain, most of the important visual information is concentrated in a few coefficients, while less significant coefficients represent fine details or noise. Quantization then reduces the precision of these coefficients, discarding information that is less perceptible to the human eye. Entropy coding, such as Huffman coding or arithmetic coding, is applied as a final step to represent the quantized coefficients efficiently.

Intra-frame coding is a fundamental component of most video compression standards, including MPEG and H.26x. It provides a baseline level of compression for each frame, ensuring that even if inter-frame prediction is not effective (e.g., at scene changes), the video data can still be compressed. While it doesn't achieve the same compression ratios as inter-frame coding, its independence from other frames makes it crucial for error resilience and random access to video content. Key frames in many video formats are entirely intra-coded.